During implementation of a Multiprotocol Label Switching virtual private network (MultiProtocol Label Switching Virtual Private Network, MPLS VPN for short), VPN members at different locations are connected through an MPLS backbone network, for example, a first VPN member and a second VPN member are connected, where the first VPN member and the second VPN member are connected to a same VPN through an MPLS backbone network. The first VPN member is connected to a first provider edge (Provider Edge, PE for short) device of the MPLS backbone network by using a first customer edge (Customer Edge, CE for short) device, the first PE device is connected to a second PE device through the MPLS backbone network, and the second PE device is connected to the second VPN member by using a second CE. The first VPN member and the second VPN member may perform communication through a path that is formed by the first CE, the first PE, the MPLS backbone network, the second PE, and the second CE.
In the MPLS backbone network, multiple topologies having different quality of service (Quality of Service, QoS for short) may be obtained by means of division. For example, in the MPLS backbone network, a first topology and a second topology having different QoS are obtained by means of division. In the prior art, when different VPN members are connected through the MPLS backbone network, different topologies of the MPLS backbone network may be selected for traffic in different directions. For example, a packet sent by the first VPN member to the second VPN member is transmitted by using the first topology of the MPLS backbone network, and a packet sent by the second VPN member to the first VPN member is transmitted by using the second topology of the MPLS backbone network, which results in inconsistency of quality of service between two communications ends of a same VPN, thereby reducing quality of service of the VPN.
In addition, with continuous development of MPLS VPN technologies, on a VPN member side, a user needs logical topologies that are used for bearing different service flows and obtained by means of division in a VPN, for example, logical topologies used for bearing service flows such as a voice, a video, and data. A VPN can be implemented only when VPN members at different locations select a jointly supported topology during connection. For example, a first VPN member selects a topology 1 used for bearing a voice service flow, a second VPN member needs to select the topology 1 (a same topology ID indicates that a topology bears a same service flow) used for bearing a voice service flow. Only in this way, the first VPN member and the second VPN member can constitute a same VPN. Otherwise, if the first VPN member selects the topology 1 and the second VPN member selects a topology 2 used for bearing a video service flow, the two VPN members cannot constitute a VPN. However, in the prior art, when multi-topology VPN members at different locations are connected in an MPLS VPN, it cannot be ensured that the VPN members select a jointly supported topology, so that an MPLS VPN cannot be implemented when VPN members at two ends of an MPLS backbone network have multiple topologies, and a user requirement cannot be met.